Arrangement for the determination of liquid levels

ABSTRACT

A fluidic level sensor in which a stream of energy fluid is alternatively diverted between two discharge channels by a control channel. One of the discharge channels is connected to an indicator, and the control channel is connected to a hollow probe which is adapted to have its free end closed by the surface of the fluid material being sensed. A branch channel is provided between the supply line of the fluid of the device and the control channel to permit the use of the supplied energy fluid to divert the stream into a selected discharge channel, the line is controlled by a pair of valves having a small hole therebetween opening to the atmosphere.

DETERMINikTlON OF LIQUID LEVELS 73*290. SR 5 7 01-23-43 OR 3 712,136Uliiftl States Fife 1 7 1 1 1111 3,712,136 Monsen 1 Jan. 23, 1973 1541ARRANGEMENT FOR THE 3,578,010

5/1971 Campagnuolo ..137/8 1.5

Primary Examiner-Louis R. Prince Assistant Examiner-Denis E. CorrAtt0mey-Howson & Howson [57] ABSTRACT A fluidic level sensor in which astream of energy fluid is alternatively diverted between two dischargechannels by a control channel. One of the discharge channels isconnected to an indicator, and the control channel is connected to ahollow probe which is adapted to have its free end closed by the surfaceof the fluid material being sensed. A branch channel is provided betweenthe supply line of the fluid of the device and the control channel topermit the use of the supplied energy fluid to divert the stream into aselected discharge channel, the line is controlled by a pair of valveshaving a small hole therebetween opening to the atmosphere.

3 Claims, 1 Drawing Figure [75] Inventor: Per Reidar Manse-1,08161,Norway [73] Assignee; Navalco A/S ['22] 'Fiid; Sept. 22'', 1970 [21]Appl. No.1 74,262

[52] US. Cl. ..73/290, 73/298, 137/815 [51] Int. Cl..." ..G0lf 23/16[58] Field of Search ..73/298, 290; 137/815; 116/118, 109, 112; 33/126.7A

[56] References Cited UNlTEDSTATES PATENTS 3,277,914 10/1966 Manion..l37/8l.5 1,116,328 11/1914 Rockwood .....116/112 2,865,320 12/1958Thiemann 16/1 12 1,289,755 12/1918 Haynes ..73/298 494,467 3/1893Donathen ..73/298 PATENTEDJMZa I975 3.712.136

INVENTOR ilsrfsmm M ATTORNEYS ARRANGEMENT FOR THE DETERMINATION OFLIQUID LEVELS The present invention relates to an arrangement for thedetermination of liquid levels by means of a probe. When measuring thelevel of the liquid in tanks for instance bunker oil tanks on boardships where great risk is present for ignition of explosive gas mixturesit is undesirable to use liquid level measuring devices compris ingelectrical means. An electrical arrangement will have to be safeguardedagainst extern flashover or against technical failure which can resultin ignition, and such safeguarding is very complicated as well asexpensive and can hardly be made so that it satisfies the rigoroussafety rules which are in force on board ships.

An object of the invention is to provide a liquid level measuringarrangement having a probe of such a kind that the abovementioned drawbacks are fully eliminated. This is in accordance with the inventionobtained by an arrangement of the type mentioned above which ischaracterized by a pressure sensitive member to which is connectedaprobe in the form of a tube, hose or the like, and alarm means, whichpressure sensitive member changes its state when the free end of theprobe is closed-by the surface of the liquid whereby a pressure changearise in the tube, hose or the like and where the alarm means issensitive as to change of state in the pressure sensitive member.

It is thus provided an arrangement comprising a probe which entirelyeliminates risk of ignition of flammable gas mixtures by technicalfailure, the probe working in accordance with a pneumatic principle.

The invention now will be further described in connection with anembodiment in accordance with the invention schematically shown in thedrawing.

A source of compressed air 1 feeds via a valve 2 a filter 3 and areduction valve 4 air with desired working pressure for a boundary layerfluidistor 5. The fluidistor is bistableand is provided with a pair ofopposed control stream channels 6 and 12, having discharge passages 16and 17. To the control stream channel 12 is connected a tube or a hose12', the lower end of which is provided with a probe 13 to measure thelevel of the liquid 14in a container 15.'To the control stream channel 6is connected a reduction valve for the compensation of the flowresistance in the tube 12. This reduction valve discharges into theambient air. In a branch channel between the inlet channel of thefluidistor and the control channel 12 ar e arranged valves 7 and 9 whichcan be of the automatically closing type. When the valves 7 and 9 areclosed one will due to the small hole 8 in the wall of the branchchannel maintain the atmospheric pressure between said valves so that aleak in the valves 7 and 9 will not result in increased pressure in thecontrol channel 12. The outlet 16 of the fluidistor discharges intoambient air while the outlet 17 is connected to an optical alarm member11 and an acoustic alarm member which both are driven pneumatically.

The tube or hose can be provided with graduation which indicates thedistance from the probe 13 which. can be constituted by a metal probehaving greater diameter than the tube or hose and serves as a lead for ithe lowering of the free end of the hose towards the liquid surface inthe container. The greater diameter of the probe 13 prevents itsclogging.

The arrangement has the following mode of operation: The valve 2 isopened so that air can flow through the fluidistor 5 and out through theoutlet 16 or 17. The way chosen by the stream of air will be accidental.If air flows through the outlet 17 the valves 7 and 9 are opened. Thehole 8 has so little diameter that the air through the valve 7 due toits great rate of flow will flow into the hose. The primer flow in thefluidistor is then controlled due to over pressure in the control streamchannel 12 towards the outlet 16. The valves 7 and 9 are then closed,for example automatically, and the hose carrying the probe 13 isintroduced in the tank or container 15 in which the level of the liquid14 should be measured. When the probe arrives at the liquid surface,under pressure will be formed in the hose, and the primer stream throughthe fluidistor 5 is controlled towards the channel 17 whereby the alarmmember 11 and 10 are activated. When the alarm is activated, one canread off the graduation of the hose which reading states the distancefrom the level of the liquid to the top of the tank.

After having read said distance the probe 13 is raised above the levelof the liquid and valves 7 and 9 are opened. Thereby the primer streamthrough the fluidistor 5 is again controlled towards the outlet 16. Thearrangement is now ready for a new descision of liquid level.

Air which can flow through the valves 7 and 9 serves also to blowthrough the hose l2 and the probe 13 to prevent clogging of thesedevices.

Even if the arrangement in accordance with the invention here isdescribed using a fluidistor it will be understood that any kind ofpressure sensitive means reacting on the closing of the free opening ofthe probe can be used. Further it is to be understood that any kind ofalarm devices, or other type of signal means can be used forthe-registration of change as to state of the pressure sensitive member.Further in stead of the flexible hose one can use a rigid tube or acombination of tube and hose if so is desirable.

Iclaim:

1. An arrangement for the determination of the level of the surface of afree flowing material comprising a hollow probe having a free endadapted to be closed by said surface, a fluidistor onto which thepneumatic probe is connected, and an indicating device, which fluidistorchanges its state when the free end of the probe is closed and apressure change occurs in the probe, and which indicating device isactivated by the said change of state in the fluidistor, characterizedin that the fluidistor includes a conduit for connection with an energystream from a separate source, two energy stream discharge channels toone of which the indicating device is connected, a control channel towhich the probe is connected for selectively controlling the flowalternatively into said two discharge channels,

a direct channel arranged between the conduit and the anibient air intosaid direct channel between said valves.

2. An arrangement according to claim 1, charac terized in that thefluidistor comprises a bistable fluidistor having a second controlchannel and a reduction valve connected in said second control channel,at least one of said direct channel valves being also a reduction valve.

3. An arrangement according to claim 1 in which 5 said control channelcomprises a hose or tube, characterized in that the probe is constitutedby a metallic sleeve having greater diameter than the diameter of thehose or tube.

1. An arrangement for the determination of the level of the surface of afree flowing material comprising a hollow probe having a free endadapted to be closed by said surface, a fluidistor onto which thepneumatic probe is connected, and an indicating device, which fluidistorchanges its state when the free end of the probe is closed and apressure change occurs in the probe, and which indicating device isactivated by the said change of state in the fluidistor, characterizedin that the fluidistor includes a conduit for connection with an energystream from a separate source, two energy stream discharge channels toone of which the indicating device is connected, a control channel towhich the probe is connected for selectively controlling the flowalternatively into said two discharge channels, a direct channelarranged between the conduit and the control channel and at least twovalves spaced apart in said direct channel for controlling the admissionof the energy stream into said control channel, and a small holeintermediate said valves to provide a passage for ambient air into saiddirect channel between said valves.
 2. An arrangement according to claim1, characterized in that the fluidistor comprises a bistable fluidistorhaving a second control channel and a reduction valve connected in saidsecond control channel, at least one of said direct channel valves beingalso a reduction valve.
 3. An arrangement according to claim 1 in whichsaid control channel comprises a hose or tube, characterized in that theprobe is constituted by a metallic sleeve having greater diameter thanthe diameter of the hose or tube.